Neonatal Anemia PDF
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Neonatal Anemia: Recognizing Thalassemia and Hemoglobin Variants James H. Nichols, PhD, DABCC, FACB Professor of Pathology, Microbiology, and Immunology Medical Director, Clinical Chemistry Associate Medical Director of Clinical Operations Vanderbilt University School of Medicine Nashville, TN 37232‐5310 [email protected] Objectives • Describe hemoglobin genetics • Interpret hemoglobin chromatograms and IEF • Recognize common hemoglobin variants Case • 4 mo male, African American, abnormal newborn screen, seen for follow‐up testing • Newborn screen shows hemoglobin FS at birth HbF = 33.8% HbA = <1% HbA2 = 2.7% HbS = 62.5% SickleDex = Positive C S F A NB Audience Poll • What do these results indicate? A. Normal profile B. Abnormal amounts of hemoglobin F C. Sickle cell disease D. Sickle cell trait Hemoglobin Tetramer Chromosomal Organization of Globin Genes Normal Hemoglobins in Adults Hemoglobin Concentration Structure Hb A ~90% 2 2 Hb F ~1.0% 2 2 Hb A2 ~2.5% 2 2 Hb A1 ~7.0% Mixture of post- translational variants of Hb A Globin Chain Expression Reasons for Requesting Hemoglobin Variant Analysis • Follow‐up to abnormal newborn screen • Adoption • Prenatal screening – patients of ethnic origin • Anemia of unknown origin in ethnic patient • Athletic exam for competitive sports Hemoglobinopathies 1. Structural – substitution, addition or deletion of one or more AAs in the globin chain i.e HbS, HbC, HbE, HbD, HbO, etc… 2. Thalassemia‐ quantitative defect in globin chain production i.e. alpha and Beta Thalassemia 3. Combination of 1 and 2 4. Asymptomatic disorders – i.e. Hereditary persistence of fetal Hemoglobin
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